"use strict";

/**
 * This jQuery plugin displays pagination links inside the selected elements.
 *
 * @author Gabriel Birke (birke *at* d-scribe *dot* de)
 * @version 1.2
 * @param {int} maxentries Number of entries to paginate
 * @param {Object} opts Several options (see README for documentation)
 * @return {Object} jQuery Object
 */
jQuery.fn.pagination = function (maxentries, opts) {
  opts = jQuery.extend({
    items_per_page: 10,
    num_display_entries: 10,
    current_page: 0,
    num_edge_entries: 0,
    link_to: "#",
    prev_text: "Prev",
    next_text: "Next",
    ellipse_text: "...",
    prev_show_always: true,
    next_show_always: true,
    callback: function callback() {
      return false;
    }
  }, opts || {});
  return this.each(function () {
    /**
     * Calculate the maximum number of pages
     */
    function numPages() {
      return Math.ceil(maxentries / opts.items_per_page);
    }
    /**
     * Calculate start and end point of pagination links depending on 
     * current_page and num_display_entries.
     * @return {Array}
     */


    function getInterval() {
      var ne_half = Math.ceil(opts.num_display_entries / 2);
      var np = numPages();
      var upper_limit = np - opts.num_display_entries;
      var start = current_page > ne_half ? Math.max(Math.min(current_page - ne_half, upper_limit), 0) : 0;
      var end = current_page > ne_half ? Math.min(current_page + ne_half, np) : Math.min(opts.num_display_entries, np);
      return [start, end];
    }
    /**
     * This is the event handling function for the pagination links. 
     * @param {int} page_id The new page number
     */


    function pageSelected(page_id, evt) {
      current_page = page_id;
      drawLinks();
      var continuePropagation = opts.callback(page_id, panel);

      if (!continuePropagation) {
        if (evt.stopPropagation) {
          evt.stopPropagation();
        } else {
          evt.cancelBubble = true;
        }
      }

      return continuePropagation;
    }
    /**
     * This function inserts the pagination links into the container element
     */


    function drawLinks() {
      panel.empty();
      var interval = getInterval();
      var np = numPages(); // This helper function returns a handler function that calls pageSelected with the right page_id

      var getClickHandler = function getClickHandler(page_id) {
        return function (evt) {
          return pageSelected(page_id, evt);
        };
      }; // Helper function for generating a single link (or a span tag if it's the current page)


      var appendItem = function appendItem(page_id, appendopts) {
        page_id = page_id < 0 ? 0 : page_id < np ? page_id : np - 1; // Normalize page id to sane value

        appendopts = jQuery.extend({
          text: page_id + 1,
          classes: ""
        }, appendopts || {});

        if (page_id == current_page) {
          var lnk = jQuery("<span class='current'>" + appendopts.text + "</span>");
        } else {
          var lnk = jQuery("<a>" + appendopts.text + "</a>").bind("click", getClickHandler(page_id)).attr('href', opts.link_to.replace(/__id__/, page_id));
        }

        if (appendopts.classes) {
          lnk.addClass(appendopts.classes);
        }

        panel.append(lnk);
      }; // Generate "Previous"-Link


      if (opts.prev_text && (current_page > 0 || opts.prev_show_always)) {
        appendItem(current_page - 1, {
          text: opts.prev_text,
          classes: "prev"
        });
      } // Generate starting points


      if (interval[0] > 0 && opts.num_edge_entries > 0) {
        var end = Math.min(opts.num_edge_entries, interval[0]);

        for (var i = 0; i < end; i++) {
          appendItem(i);
        }

        if (opts.num_edge_entries < interval[0] && opts.ellipse_text) {
          jQuery("<span>" + opts.ellipse_text + "</span>").appendTo(panel);
        }
      } // Generate interval links


      for (var i = interval[0]; i < interval[1]; i++) {
        appendItem(i);
      } // Generate ending points


      if (interval[1] < np && opts.num_edge_entries > 0) {
        if (np - opts.num_edge_entries > interval[1] && opts.ellipse_text) {
          jQuery("<span>" + opts.ellipse_text + "</span>").appendTo(panel);
        }

        var begin = Math.max(np - opts.num_edge_entries, interval[1]);

        for (var i = begin; i < np; i++) {
          appendItem(i);
        }
      } // Generate "Next"-Link


      if (opts.next_text && (current_page < np - 1 || opts.next_show_always)) {
        appendItem(current_page + 1, {
          text: opts.next_text,
          classes: "next"
        });
      }
    } // Extract current_page from options


    var current_page = opts.current_page; // Create a sane value for maxentries and items_per_page

    maxentries = !maxentries || maxentries < 0 ? 1 : maxentries;
    opts.items_per_page = !opts.items_per_page || opts.items_per_page < 0 ? 1 : opts.items_per_page; // Store DOM element for easy access from all inner functions

    var panel = jQuery(this); // Attach control functions to the DOM element 

    this.selectPage = function (page_id) {
      pageSelected(page_id);
    };

    this.prevPage = function () {
      if (current_page > 0) {
        pageSelected(current_page - 1);
        return true;
      } else {
        return false;
      }
    };

    this.nextPage = function () {
      if (current_page < numPages() - 1) {
        pageSelected(current_page + 1);
        return true;
      } else {
        return false;
      }
    }; // When all initialisation is done, draw the links


    drawLinks(); // call callback function

    opts.callback(current_page, this);
  });
};